The mean weight of newborn infants at a community hospital is 6.6 pounds.A sample of seven infants is randomly selected and their weights at birth are recorded as 9.0,7.3,6.0,8.8,6.8,8.4,and 6.6 pounds.What is the sample standard deviation?
A)1.177
B)6.6
C)1.385
D)7.6

Question

Quizplus · Accepted Answer

The sample standard deviation is 1.177 pounds. This can be calculated using the formula:s = sqrt(sum((x - mean)^2) / (n - 1))where:s is the sample standard deviationx is each data pointmean is the sample meann is the sample sizeIn this case, the sample mean is 7.4 pounds. Plugging this into the formula, we get:s = sqrt(sum((x - 7.4)^2) / (7 - 1))= sqrt(sum((9.0 - 7.4)^2 + (7.3 - 7.4)^2 + (6.0 - 7.4)^2 + (8.8 - 7.4)^2 + (6.8 - 7.4)^2 + (8.4 - 7.4)^2 + (6.6 - 7.4)^2) / (7 - 1))= sqrt(sum(1.6^2 + (-0.1)^2 + (-1.4)^2 + 1.4^2 + (-0.6)^2 + 1.0^2 + (-0.8)^2) / 6)= sqrt(sum(2.56 + 0.01 + 1.96 + 1.96 + 0.36 + 1.00 + 0.64) / 6)= sqrt(8.49 / 6)= sqrt(1.415)= 1.177

The Mean Weight of Newborn Infants at a Community Hospital